Following the company’s confirmation of its unsolicited offer for Monsanto, Bayer faced a backlash from major shareholders and fund managers. One of the most vocal critics, John Bennett of Henderson Global Investors, called the decision to buy the US seeds giant “immediate destruction” of shareholder value.”

In comments emailed to international media, Bennett said he was “furious” that new CEO Werner Baumann had not engaged with him first, adding that the “fine work” of Baumann’s predecessor Marijn Dekkers has been “ripped up.”

“I had hoped that the days of such arrogant empire-building and ignorance of the actual owners of the business were at an end,” media outlets quotes Bennett as saying, adding his remarks that “the board of Bayer should be considering the CEO's position."

Bennett’s comments mark “the most scathing attack yet on Bayer in a chorus of investor discontent mainly over the sheer size of the proposed deal,” the news agency Reuters said.

Among critics in the latter category, Markus Manns, Frankfurt, Germany-based Union Investment fund manager, also expressed skepticism about the logic of the planned transaction. While saying he sees “strategic value in adding a large seeds business to Bayer’s crop-chemicals unit, Manns said he believes the size of the deal would stretch Bayer’s finances too much.”

Another fund manager, Maximillian Anderl of UBS Global Asset Management, said he was "deeply concerned" about the Bayer bid, and would prefer a joint venture or a nil-premium merger. Other shareholders commented that they were concerned about the dilutive effect of a possible equity increase to fund the deal. Some news sources have suggested that Bayer may offer a mix of cash and stock.

Several commentators said they thought the high acquisition price would leave Bayer with insufficient funds to spend on pharmaceuticals. “After a Monsanto deal, it can largely be ruled out for Bayer to retain the financial flexibility over the next two to three years for acquisitions in the pharma market,” said Manns.

Analyst Alistair Campbell of Berenberg offered the perspective that “Bayer’s pharma business is in excellent health today, but the clock is ticking regarding rebuilding its pipeline and recent newsflow has been disappointing.”

After plunging initially by 8% on the news, Bayer shares closed 1.2% higher in Frankfurt on May 20, the first trading day after the bid was confirmed.